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Combined Emission Characteristics and Control Technology of Gob Gas in Ultra-Close Seams
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Procedia Engineering
ProcediaProcedia Engineering 00 (2011) Engineering 26 000–000 (2011) 1194 – 1199 www.elsevier.com/locate/procedia
First International Sympos ium on Mine Safety Science and Engineering
Combined emission characteristics and control technology of gob gas in ultra-close seams Zhang Shoubao, Zhang Hui, Xie Shengrong, He Fulian a* College of Resources & Safety Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
Abstract It is well known that the upper gob gas will gush to working face together with gob gas in mining seam when the lower seam is mined in ultra-close seams. When the layer thickness between two seams is small, the two gobs will become one after the layer collapse, and then the higher concentration gas in upper closed gob will gush out into working face under the negative pressure, which can cause the overrun of gas. The exiting gas problems of lower mining coal in ultra-close seam were analyzed, and then the combined emission characteristic and the reasons of gas overrun were drawn out. In view of this situation, using constant pressurized ventilation (CPV) of windscreen-fan regulator of joint air-pressure, the fans were equipped in haulage roadway and adjustable windscreens were set up in return roadway. In 1001 face, increasing pressure and reducing air volume were implemented by this method; the airflow vectors circuits of before and after using constant pressurized ventilation were analyzed. The practical results showed that the technology of constant pressurized ventilation solved the gas problem successfully, and got the safe effect in this face.
© 2011 Published by Elsevier Ltd. Select ion and/or peer-review under responsibility of China Academy of Safety Science and Technology, China Un iversity of M ining and Technology(Beijing), McGill University and University of Wollongong. Keywords: ultra-close seams; gas; combined emission; constant pressurized ventilation;
1. Introduction China is one of the most serious countries which suffer gas disasters in the world, and gas is the main reason that could cause the security incidents [1-2]. Especially after the upper seam was mined in u ltra-
* Corresponding author. Tel.: +8613811990997. E-mail address: [email protected].
1877-7058 © 2011 Published by Elsevier Ltd. doi:10.1016/j.proeng.2011.11.2290
Zhang al.al/ / Procedia – 1199 ZhangShoubao Shoubaoet et ProcediaEngineering Engineering26 00(2011) (2011)1194 000–000
2
close seams, its gob became one close space, and then the gas concentration became h igher and higher. While the lower seam was mined, with the collapse of roof, the upper gob gas would gush into min ing seam to increase difficulty to control it in the face [3-4]. In the world, for controlling the gas, there have many control methods in addition to conventional methods of ventilation such as comprehensive drainage control methods, which solve many high-gas coal mine gas management problems [5-7]. In one coal mine, during the period of min ing the lower seam, with the collapse of direct roof, the gas concentration at the face became h igher to limited value, and then the working face must stop working. It is tested that the gas is fro m t wo gobs, and the double gobs combine makes the face appear ventilat ion leakage. Fo r solving the gas and the air leakage problems, the technology of constant pressurized ventilation was put forward to control them. 2. Current situation and problems of lower mini ng seam There are No.9 and No.10 coal seam in one mine, and its interval layer th ickness is fro m 0.4m to 3.2m, and its average thickness is 2.0m. They belong to ultra-close coal seam. 901 face and 903 face of No.9 coal seam were separately mined over in 2006 and 2008. 1001 face of No.10 coal face was designed to put under the 901 and 903 gobs, and its roadways are parallel to roadways of 901 face with interval of 30m. The absolute outflow of gas in 1001 face is 2.8m3/ min. The spatial co mparison relationships of above three faces are shown in Figure 1. 901 return roadway
1001 return roadway 901 face 901 haulage roadway 903 return roadway
903 face
Fig. 1. Spatial comparison chart of 1001 to 901 and 903 face
average gas concentration（%）
early mining
after roof falls
1.5 1.0 0.5 0.0 haulage roadway
15# support
35# support
55# support
75# support
upper corner
measure point place
Fig. 2. Average gas concentration value curves of early mining and after roof falls
return roadway
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At the early min ing of 1001 face, the results of tested gas data showed the concentration is normal, but after the direct roof fell partly, the gas concentration increased rapidly at the fallen place. The average gas concentration value curve of every measure point along the air flow line before and after roof fallen were drawn out in Figure 2. In the figure, it is shown that at early mining of 1001 face, the gas concentration increased fro m 0.14% at the haulage roadway to 0.65% at upper corner of the face; wh ile the roof fell completely, the gas concentrations at many places in the face were higher than 0.75%, and the highest value of upper corner is higher than 1%. Because the 1001 face was mined, the roof fell caused the surrounding rock over the face occur c corresponding movement. In addition, the face is not more than 200m under the surface; it is possible that the face connect the ground surface by gob and rock cracks, wh ich cause large amount air leakage. The measured air intake is 710m3 / min, and air-return quantity is 1187m3 /min, the air leakage quantity is more than 470m3 / min. The measured gas concentration in return roadway is higher than 1.3% for a long time which makes the face stop production. 3. Analysis on combined gas emission characteristics Based on the investigation and analysis of geological and productive conditions and gas occurrence, the gas sources were analyzed, and then the reasons that cause the gas concentration beyond the limit value were as fallowing: (1) The direct roof is very thin; the thinnest place is only 0.4m, when it falls, the collapse rock in No.9 gob will fall into 1001 gob, so the caving zone of 1001 face includes two seams’ gobs. With the movement of rock over the face and ventilating negative pressure, the gas in the upper gob flowed to the mining space of 1001 face, and the schematic d iagram of gas moved direct ion is shown as Figure 3.
Gob of No.9 coal
Combined gobs of No.9 and 10 coal
No.10 coal
Fig. 3. Schematic diagram of gas moved direction in gobs
(2) The depth of 1001 face is less than 200m, and there have gobs of No.8 and No.9 coal over it. When the No.10 coal was mined, the crack zone was connected with the ground fissures. Because the surface pressure is higher than the pressure at the 1001 face, the air will flow fro m ground surface to 1001 gob and face, so the air can take amount of gas in the gob to face and return roadway to make the gas concentration beyond the limit value. In summary, as the direct roof collapsed after the No.10 coal was mined, the gas of two gobs combined together into 1001 face under the action of air leakage.
3
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Zhang al.al/ / Procedia – 1199 ZhangShoubao Shoubaoet et ProcediaEngineering Engineering26 00(2011) (2011)1194 000–000
4. Research on technol ogy of constant pressurized ventilati on in 1001 face 4.1. Choice of technology of constant pressurized ventilation For solving the gas and air leakage prob lems, the methods of increasing air quantity and installing adjustable windscreens at the return roadway were used to control the gas concentration, but they did not gain the satisfactory effect. The technology of constant pressurized ventilat ion for controlling gas is developed from using it to prevent fire in coal mine. Its theory is to adjust the air quantity or air pressure along the air flow line by installing the equip ments artificially. There are three methods to achieve constant pressure as fallowing: (1) Installing adjustable windscreen at the air flow line. Its essence is to reduce the air quantity and increase air pressure, change the pressure distribution along the working face to gain the purpose of constant pressure. (2) Installing the local fan with air door. Its essence is to change the pressure distribution along the air flow line by using the local fan to increase air quantity and pressure. (3) Un ited pressure regulator of windscreen and local fan. It includes two ways as increasing pressure and reducing pressure. The first way is to install the local fan at the upcast of adjustable windscreen, which can gain the effect of increasing the pressure along the air flo w line. The second way is to install the adjustable windscreen at the upcast of local fan, which can get the effect of reducing the pressure between the two equipments. Based on the comprehensive analysis of gas treatment technologies and air leakage control methods, combined with local situations, the united pressure regulator of windscreen and local fan was chosen. The concrete way is to install local fans at the haulage roadway and windscreens at the return roadway to make the leakage and gas controlled. 4.2. Design parameters of constant pressurized ventilation in 1001 face Because the air leakage reason is main ly caused by the caving crack connected to ground surface, firstly, the waste mine mouth and cracks on the surface subsidence area of 901 and 903 face were filled and plugged to reduce the leakage fro m ground surface; secondly, the air-sealed walls of roadways of No.9 coal seam were checked and filled to stop leakage fro m roadways of No.9 coal seam; lastly, the parameters of constant pressurized ventilation were designed as fallowing: (1) One sealed wall was built at the 5m and 20m to the entry of 1001 haulage roadway, and there is an air door of 1000* 600mm for safe exit on it. (2) There is one hole reserved on each sealed wall for installing the air pipe. The hole d iameter is 1000mm. (3) Two groups of four local fans were installed in the connecting slot to 1001 haulage roadway. The type of local fan is BDKJ-No.6.3. (4) The air pipe is fro m the local fan to the p lace of 5m inner to 20m sealed wall. The air pipe length is no shorter than 50m. (5) Two windscreens were set up at the exit of 1001 return roadway. Their separation distance is 20m. 5. Practice and result of constant pressurized ventil ation in 1001 face After the two regulators were built comp letely, the technology of constant pressurized ventilation was on trial. The way used is increasing pressure and decreasing air quantity. Using this method not only can reduce the leakage distance that the fresh air flo ws into the gob, so but also increase the face pressure to
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make it no lower than the leakage point pressure of whole ventilation system. It can reduce the gas which be taken with by both the fresh air and the leakage air to the face, so the face gas concentration could decline to make the face safe. The air flow d irection and area changed obviously before and after the imp lementation of constant pressurized ventilat ion, the diagrams are shown in Figure 4. leakage point return roadway
leakage point return roadway
gob
haulage roadway
working face
working face
gob
haulage roadway (a)
(b)
Fig. 4. (a) Air flow direction diagram before implementation of constant pressurized ventilation; (b) Air flow direction diagram after implementation of constant pressurized ventilation
Fro m the Figure 4(a), it is can be seen that before imp lementation of constant pressurized ventilat ion, the air leakage d istance of fresh flo w to the gob is deep, and its coverage area is large. So with it came back to the face and return roadway, it had taken lots of gas to the return air. At the same time, as there are many air quantity of more than 400m3 /min fro m the gob, it is bound to carry mo re gas fro m the deep gob. Both of those two parts gas and the gas from the coal rib make the gas at the upper corner and return roadway higher, even exceeding the limit value. Fro m the Figure 4(b), it is can be seen that because of reducing air quantity, the depth and the area of fresh air into the gob reduce too, so the unit leakage quantity is reduced to take less gas of lo wer gob. Simu ltaneously, the air pressure at the face was increased to no lo wer than the pressure value of air leakage point in deep gob, so the air quantity flow fro m air leakage point to face is reduced or stopped to control the gas concentration in face or return roadway. At the period of min ing time after imp lement of constant pressurized ventilation, some stations were set along the air flow line to measure gas concentrations and air quantity. The results show that the air intake remained at 570-600m3 / min, and air-return quantity remained between 480m3 / min to 600m3 / min; the gas concentration while mining was at 0.3% to 0.6%, and 1001 face achieved the safe production. 6. Conclusions It is necessary to mine the lower seam when the upper seam was mined over in ultra-close seams. The gas concentration is always exceeding the limit value when the No.10 seam was mining. The main gas sources are gob of N0.9 coal seam and gob of N0.10 coal seam. The gas of both gobs combined and gushed into the face to make the gas concentration higher. The technology of constant pressurized ventilation was brought forward. The method is to install local fans at the haulage roadway and windscreens at the return roadway. It can reduce the gas which be taken
6
Zhang al.al/ / Procedia – 1199 ZhangShoubao Shoubaoet et ProcediaEngineering Engineering26 00(2011) (2011)1194 000–000
with by both the fresh air and the leakage air to the face, so the face gas concentration could decline to make the face safe. Acknowledgements The research work is financially supported by the Fundamental Research Funds for the Central Universities (2009QZ10), the National Basic Research Program of China (2010CB226802), and the State Key Laboratory of Coal Resources and Safe Mining (CUMT). References [1] ZHOU Shi-ning, LIN Bai-qua. Prevention and control theory for gas dynamical disaster of coal mine . Beijing: Science Press, 2007. (in Chinese) [2] YUAN Liang. Theory and technology of gas drainage and capture in soft multiple coal seam of low permeability . Beijing: China Coal Industry Publishing House, 2004. (in Chinese) [3] YU Qi-xiang, CHEN Yuan-ping, JIANG Chenglin, et al. Principles and applications of exploitation of coal and pressure relief gas in thick and high-gas seams. Journal of China University of Mining and Technology, 2004,vol.33(2):127-131. (in Chinese) [4] ZHAO Yao-jiang, XIE Sheng-rong, WEN Bai-gen.et al. Gas drainage technique by 1000m long and large diameter roof boreholes in high gas coal seam group. Journal of China coal society. 2009, vol.34(6):797-801. (in Chinese) [5] XIE Sheng-rong, WEN Bai-gen, HE Fu-lian. Study on drainage technology by 1000m long roof boreholes in strike of high methane coal seam group,2008-09-01,Progress in safety science and technology:VOL.Ⅶ.Beijing:science press:1501-1505. [6] WANG Dong-sheng. Simulation of gas flow rule at three-dimensional drainage under close-distance seam group mining. Journal of China coal society. 2011, vol.36(1):86-90. (in Chinese) [7] LIN Bai-quan, ZHANG Jian-guo, ZHAI Cheng. et al. Gas Emission and Distribution Law in the Stope Mining Short Range Protection Layer Using Downward Ventilation. Journal of China University of Mining and Technology, 2008,vol.37(1):24-28. (in Chinese)
1199
Procedia Engineering
ProcediaProcedia Engineering 00 (2011) Engineering 26 000–000 (2011) 1194 – 1199 www.elsevier.com/locate/procedia
First International Sympos ium on Mine Safety Science and Engineering
Combined emission characteristics and control technology of gob gas in ultra-close seams Zhang Shoubao, Zhang Hui, Xie Shengrong, He Fulian a* College of Resources & Safety Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
Abstract It is well known that the upper gob gas will gush to working face together with gob gas in mining seam when the lower seam is mined in ultra-close seams. When the layer thickness between two seams is small, the two gobs will become one after the layer collapse, and then the higher concentration gas in upper closed gob will gush out into working face under the negative pressure, which can cause the overrun of gas. The exiting gas problems of lower mining coal in ultra-close seam were analyzed, and then the combined emission characteristic and the reasons of gas overrun were drawn out. In view of this situation, using constant pressurized ventilation (CPV) of windscreen-fan regulator of joint air-pressure, the fans were equipped in haulage roadway and adjustable windscreens were set up in return roadway. In 1001 face, increasing pressure and reducing air volume were implemented by this method; the airflow vectors circuits of before and after using constant pressurized ventilation were analyzed. The practical results showed that the technology of constant pressurized ventilation solved the gas problem successfully, and got the safe effect in this face.
© 2011 Published by Elsevier Ltd. Select ion and/or peer-review under responsibility of China Academy of Safety Science and Technology, China Un iversity of M ining and Technology(Beijing), McGill University and University of Wollongong. Keywords: ultra-close seams; gas; combined emission; constant pressurized ventilation;
1. Introduction China is one of the most serious countries which suffer gas disasters in the world, and gas is the main reason that could cause the security incidents [1-2]. Especially after the upper seam was mined in u ltra-
* Corresponding author. Tel.: +8613811990997. E-mail address: [email protected].
1877-7058 © 2011 Published by Elsevier Ltd. doi:10.1016/j.proeng.2011.11.2290
Zhang al.al/ / Procedia – 1199 ZhangShoubao Shoubaoet et ProcediaEngineering Engineering26 00(2011) (2011)1194 000–000
2
close seams, its gob became one close space, and then the gas concentration became h igher and higher. While the lower seam was mined, with the collapse of roof, the upper gob gas would gush into min ing seam to increase difficulty to control it in the face [3-4]. In the world, for controlling the gas, there have many control methods in addition to conventional methods of ventilation such as comprehensive drainage control methods, which solve many high-gas coal mine gas management problems [5-7]. In one coal mine, during the period of min ing the lower seam, with the collapse of direct roof, the gas concentration at the face became h igher to limited value, and then the working face must stop working. It is tested that the gas is fro m t wo gobs, and the double gobs combine makes the face appear ventilat ion leakage. Fo r solving the gas and the air leakage problems, the technology of constant pressurized ventilation was put forward to control them. 2. Current situation and problems of lower mini ng seam There are No.9 and No.10 coal seam in one mine, and its interval layer th ickness is fro m 0.4m to 3.2m, and its average thickness is 2.0m. They belong to ultra-close coal seam. 901 face and 903 face of No.9 coal seam were separately mined over in 2006 and 2008. 1001 face of No.10 coal face was designed to put under the 901 and 903 gobs, and its roadways are parallel to roadways of 901 face with interval of 30m. The absolute outflow of gas in 1001 face is 2.8m3/ min. The spatial co mparison relationships of above three faces are shown in Figure 1. 901 return roadway
1001 return roadway 901 face 901 haulage roadway 903 return roadway
903 face
Fig. 1. Spatial comparison chart of 1001 to 901 and 903 face
average gas concentration（%）
early mining
after roof falls
1.5 1.0 0.5 0.0 haulage roadway
15# support
35# support
55# support
75# support
upper corner
measure point place
Fig. 2. Average gas concentration value curves of early mining and after roof falls
return roadway
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Zhang Shoubao etProcedia al. / Procedia Engineering 26 (2011) 1194 – 1199 Zhang Shoubao et al/ Engineering 00 (2011) 000–000
At the early min ing of 1001 face, the results of tested gas data showed the concentration is normal, but after the direct roof fell partly, the gas concentration increased rapidly at the fallen place. The average gas concentration value curve of every measure point along the air flow line before and after roof fallen were drawn out in Figure 2. In the figure, it is shown that at early mining of 1001 face, the gas concentration increased fro m 0.14% at the haulage roadway to 0.65% at upper corner of the face; wh ile the roof fell completely, the gas concentrations at many places in the face were higher than 0.75%, and the highest value of upper corner is higher than 1%. Because the 1001 face was mined, the roof fell caused the surrounding rock over the face occur c corresponding movement. In addition, the face is not more than 200m under the surface; it is possible that the face connect the ground surface by gob and rock cracks, wh ich cause large amount air leakage. The measured air intake is 710m3 / min, and air-return quantity is 1187m3 /min, the air leakage quantity is more than 470m3 / min. The measured gas concentration in return roadway is higher than 1.3% for a long time which makes the face stop production. 3. Analysis on combined gas emission characteristics Based on the investigation and analysis of geological and productive conditions and gas occurrence, the gas sources were analyzed, and then the reasons that cause the gas concentration beyond the limit value were as fallowing: (1) The direct roof is very thin; the thinnest place is only 0.4m, when it falls, the collapse rock in No.9 gob will fall into 1001 gob, so the caving zone of 1001 face includes two seams’ gobs. With the movement of rock over the face and ventilating negative pressure, the gas in the upper gob flowed to the mining space of 1001 face, and the schematic d iagram of gas moved direct ion is shown as Figure 3.
Gob of No.9 coal
Combined gobs of No.9 and 10 coal
No.10 coal
Fig. 3. Schematic diagram of gas moved direction in gobs
(2) The depth of 1001 face is less than 200m, and there have gobs of No.8 and No.9 coal over it. When the No.10 coal was mined, the crack zone was connected with the ground fissures. Because the surface pressure is higher than the pressure at the 1001 face, the air will flow fro m ground surface to 1001 gob and face, so the air can take amount of gas in the gob to face and return roadway to make the gas concentration beyond the limit value. In summary, as the direct roof collapsed after the No.10 coal was mined, the gas of two gobs combined together into 1001 face under the action of air leakage.
3
4
Zhang al.al/ / Procedia – 1199 ZhangShoubao Shoubaoet et ProcediaEngineering Engineering26 00(2011) (2011)1194 000–000
4. Research on technol ogy of constant pressurized ventilati on in 1001 face 4.1. Choice of technology of constant pressurized ventilation For solving the gas and air leakage prob lems, the methods of increasing air quantity and installing adjustable windscreens at the return roadway were used to control the gas concentration, but they did not gain the satisfactory effect. The technology of constant pressurized ventilat ion for controlling gas is developed from using it to prevent fire in coal mine. Its theory is to adjust the air quantity or air pressure along the air flow line by installing the equip ments artificially. There are three methods to achieve constant pressure as fallowing: (1) Installing adjustable windscreen at the air flow line. Its essence is to reduce the air quantity and increase air pressure, change the pressure distribution along the working face to gain the purpose of constant pressure. (2) Installing the local fan with air door. Its essence is to change the pressure distribution along the air flow line by using the local fan to increase air quantity and pressure. (3) Un ited pressure regulator of windscreen and local fan. It includes two ways as increasing pressure and reducing pressure. The first way is to install the local fan at the upcast of adjustable windscreen, which can gain the effect of increasing the pressure along the air flo w line. The second way is to install the adjustable windscreen at the upcast of local fan, which can get the effect of reducing the pressure between the two equipments. Based on the comprehensive analysis of gas treatment technologies and air leakage control methods, combined with local situations, the united pressure regulator of windscreen and local fan was chosen. The concrete way is to install local fans at the haulage roadway and windscreens at the return roadway to make the leakage and gas controlled. 4.2. Design parameters of constant pressurized ventilation in 1001 face Because the air leakage reason is main ly caused by the caving crack connected to ground surface, firstly, the waste mine mouth and cracks on the surface subsidence area of 901 and 903 face were filled and plugged to reduce the leakage fro m ground surface; secondly, the air-sealed walls of roadways of No.9 coal seam were checked and filled to stop leakage fro m roadways of No.9 coal seam; lastly, the parameters of constant pressurized ventilation were designed as fallowing: (1) One sealed wall was built at the 5m and 20m to the entry of 1001 haulage roadway, and there is an air door of 1000* 600mm for safe exit on it. (2) There is one hole reserved on each sealed wall for installing the air pipe. The hole d iameter is 1000mm. (3) Two groups of four local fans were installed in the connecting slot to 1001 haulage roadway. The type of local fan is BDKJ-No.6.3. (4) The air pipe is fro m the local fan to the p lace of 5m inner to 20m sealed wall. The air pipe length is no shorter than 50m. (5) Two windscreens were set up at the exit of 1001 return roadway. Their separation distance is 20m. 5. Practice and result of constant pressurized ventil ation in 1001 face After the two regulators were built comp letely, the technology of constant pressurized ventilation was on trial. The way used is increasing pressure and decreasing air quantity. Using this method not only can reduce the leakage distance that the fresh air flo ws into the gob, so but also increase the face pressure to
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Zhang Shoubao etProcedia al. / Procedia Engineering 26 (2011) 1194 – 1199 Zhang Shoubao et al/ Engineering 00 (2011) 000–000
5
make it no lower than the leakage point pressure of whole ventilation system. It can reduce the gas which be taken with by both the fresh air and the leakage air to the face, so the face gas concentration could decline to make the face safe. The air flow d irection and area changed obviously before and after the imp lementation of constant pressurized ventilat ion, the diagrams are shown in Figure 4. leakage point return roadway
leakage point return roadway
gob
haulage roadway
working face
working face
gob
haulage roadway (a)
(b)
Fig. 4. (a) Air flow direction diagram before implementation of constant pressurized ventilation; (b) Air flow direction diagram after implementation of constant pressurized ventilation
Fro m the Figure 4(a), it is can be seen that before imp lementation of constant pressurized ventilat ion, the air leakage d istance of fresh flo w to the gob is deep, and its coverage area is large. So with it came back to the face and return roadway, it had taken lots of gas to the return air. At the same time, as there are many air quantity of more than 400m3 /min fro m the gob, it is bound to carry mo re gas fro m the deep gob. Both of those two parts gas and the gas from the coal rib make the gas at the upper corner and return roadway higher, even exceeding the limit value. Fro m the Figure 4(b), it is can be seen that because of reducing air quantity, the depth and the area of fresh air into the gob reduce too, so the unit leakage quantity is reduced to take less gas of lo wer gob. Simu ltaneously, the air pressure at the face was increased to no lo wer than the pressure value of air leakage point in deep gob, so the air quantity flow fro m air leakage point to face is reduced or stopped to control the gas concentration in face or return roadway. At the period of min ing time after imp lement of constant pressurized ventilation, some stations were set along the air flow line to measure gas concentrations and air quantity. The results show that the air intake remained at 570-600m3 / min, and air-return quantity remained between 480m3 / min to 600m3 / min; the gas concentration while mining was at 0.3% to 0.6%, and 1001 face achieved the safe production. 6. Conclusions It is necessary to mine the lower seam when the upper seam was mined over in ultra-close seams. The gas concentration is always exceeding the limit value when the No.10 seam was mining. The main gas sources are gob of N0.9 coal seam and gob of N0.10 coal seam. The gas of both gobs combined and gushed into the face to make the gas concentration higher. The technology of constant pressurized ventilation was brought forward. The method is to install local fans at the haulage roadway and windscreens at the return roadway. It can reduce the gas which be taken
6
Zhang al.al/ / Procedia – 1199 ZhangShoubao Shoubaoet et ProcediaEngineering Engineering26 00(2011) (2011)1194 000–000
with by both the fresh air and the leakage air to the face, so the face gas concentration could decline to make the face safe. Acknowledgements The research work is financially supported by the Fundamental Research Funds for the Central Universities (2009QZ10), the National Basic Research Program of China (2010CB226802), and the State Key Laboratory of Coal Resources and Safe Mining (CUMT). References [1] ZHOU Shi-ning, LIN Bai-qua. Prevention and control theory for gas dynamical disaster of coal mine . Beijing: Science Press, 2007. (in Chinese) [2] YUAN Liang. Theory and technology of gas drainage and capture in soft multiple coal seam of low permeability . Beijing: China Coal Industry Publishing House, 2004. (in Chinese) [3] YU Qi-xiang, CHEN Yuan-ping, JIANG Chenglin, et al. Principles and applications of exploitation of coal and pressure relief gas in thick and high-gas seams. Journal of China University of Mining and Technology, 2004,vol.33(2):127-131. (in Chinese) [4] ZHAO Yao-jiang, XIE Sheng-rong, WEN Bai-gen.et al. Gas drainage technique by 1000m long and large diameter roof boreholes in high gas coal seam group. Journal of China coal society. 2009, vol.34(6):797-801. (in Chinese) [5] XIE Sheng-rong, WEN Bai-gen, HE Fu-lian. Study on drainage technology by 1000m long roof boreholes in strike of high methane coal seam group,2008-09-01,Progress in safety science and technology:VOL.Ⅶ.Beijing:science press:1501-1505. [6] WANG Dong-sheng. Simulation of gas flow rule at three-dimensional drainage under close-distance seam group mining. Journal of China coal society. 2011, vol.36(1):86-90. (in Chinese) [7] LIN Bai-quan, ZHANG Jian-guo, ZHAI Cheng. et al. Gas Emission and Distribution Law in the Stope Mining Short Range Protection Layer Using Downward Ventilation. Journal of China University of Mining and Technology, 2008,vol.37(1):24-28. (in Chinese)
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